Refractory article and process of making the same



UNITED STATES PATENT OFFICE.

TIS HU'IGHIIB, OI mam FALLS, m YORK, ASSIGIOB IO m OABBOBUNDUIGOIPAII'Y, OI IIAGAIL FALLS, NEW YORK, A CORPORATION 01 VAIIA.

REFRACTORY ARTICLE AND PROCESS O! m sum.

No Drawing.

To all whom it may concern:

Be it known that I, one Ho'rcmxs a citizen of the United States residingat lliagara hi h temperature.

hromite has for a long time been success-' fully used as a refractory Inthe form of brick or granular material it has found extensive use in themetallurgical industry. Heretofore the principal bonding a' ents whichhave been employed have been finely round chromite ore, hme, or a highlyre ractory fireclay. These chromite articles are exceedingly refractoryand possess desirable chemical characteristics. However, they alsopossess a marked tendency to crack and spall when subjected to suddenchaii es of temperature, which necessitates restricting their use to aposition where temperature changes are reduced to a minimum.

I have discovered that mixtures of chromite and zirconia, when formedinto a refractory body and burned, have a very considerable resistanceto cracking and spelling when subjected to sudden changes oftemperature, and in this regard are considerably superior to chromitebricks made with other types of bonding material. This new refractory-material also chemical inactivit at high temperatures when in contactwlth corrosive slags.

In the preferred method of practising my invention I form into shapedbodies, by any well known method, a mixture of 90% of calcined chromiteand 10% of zirconia. These bodies are burned at a high temperature inany kiln of suitable design. The burned articles are extremely hard anddense and possess a marked resistance toward fracture.

For the chromite material I prefer to use a run of crusher product, 8mesh and finer Specification of Letters nun.

Application and ma :4, mo. lorlal Io. m.

ossesses marked Patented Dec. 14, 1920.

contammg as high percentage as possible of oxid. f

um ores 0 various compositions work very satisfactory but it ispreferable to use an ore which is high in chromium oxid and low in ironoxid.

For the zirconia I prefer to use a product known as zirkite cement whichconsists of a zirconium ore containing about 75% of zirconium oxidground to a fine state of subdivision.

The s ecifications mentioned above ma be modi ed very materially toproduce articles desirable for certain applications. The chromitematerial may consist of calcined chromium ore, electrically fusedchromium ore or purified chromium oxid. For the zirconia content I mause coarsely ground zirconium ore, puri ed zirconium oxid orelectrically fused zirconium ore or oxid. -I ma also use a mineral knownas zircon whlch consists largely of zirconium silicate the commercialore containing about 65% o zirconium oxid.

The relative proportions of chromite and zirconia may vary greatly andsatisfactory products can be made containing from 5 to 75% of zirconia.

The invention is not limited to the preferred chromium and zirconiummaterials or the preferred roportions, but may be otherwise embodiedwithin the scope of the following claims 5- I claim:

1. A shaped highly refractory article formed of a burned mlxturecontaming zirconia and chromite.

2. A shaped highly refractory article formed of a burned mixturecontaining zirconia and fused chromite.

3. A shaped highly refractory article formed of a burned mixturecontaming zirconia and purified chromium oxid. I

L. A shaped highly refractory article formed of a burned mixturecontaining chromium oxid and from 5 to 75% zirconia.

5. A shaped highly refractory article formed of a burned mixturecontaining crystallized zirconia and chromium oxid.

6. The process of maln'ng highly refrac- 7. The process of making highlyredinac- 9. The process of making highly refrac- 10 tory articles whichconsists in mixing zirtory articles Which consists in mixing an (oniaand chromite, the particles of chromite oxygen containing compound ofzirconium being coarsen than those of the zirconia, and chromium. oXid,forming the mixture forming mixture into shaped articles, and intoshaped articles, and burning the shaped burning the shaped articles.articles. 15

S. A refractory article formed of a burned In testimony whereof I havehereunto set mixture containing an oxygen containing my hand. compoundof zirconium and chromite. OTIS HUTCHI'NS.

